Research On One-cycle Controlled ZVS PWM Full-bridge Three-level Converter

For the system of single pneumatic generating set, the control of generated power depends on the control of load current if there is no power network, and this problem can be solved by a specific current source converter and power distribution。The control of generator torque Tg can be realized by controlling the output current ia for generator torque is in direct proportion to armature current.Therefore one-cycle control techniques are more advantageous than the traditional voltage control and current control in aspect of the quick dynamic response to the input voltage and load perturbation. So it is suitable for the specific current source converter. One-cycle control technique is a novel nonlinear control method, it is conceived to control the duty-ratio of the switch in real time so that the average value of the chopped waveform the switch rectifier is exactly equal or proportioned to the control reference. It can eliminate automatically instantaneous error in one cycle and the error belonging to the former cycle can not be brought to next cycle. One-cycle control have the merits of rapid response, invariable switch frequency, simple control circuit and easy to realization and so on.The proposing and development of multilevel converter were clarified in this dissertation. The principles of various control methods of multilevel converter were summarized in this dissertation. Analysed the principles of one-cycle control technique and compared the difference of voltage control, current control and one-cycle control. The theoretical analysis shows that one-cycle control has quick dynamic response to the input voltage and load perturbation. Emphatically analyzes the realization principle, steady operation principle, parameters design of power circuit and control circuit of the one-cycle control ZVS PWM three-level full-bridge current source and verified experimentally. Experimental results show that the control method of this converter is simple, reliable and general.In order to perfect the control strategy of three-level full-bridge current source, a new wide input voltage range one-cycle control ZVS PWM three-level full-bridge current source was proposed. Design detail, steady operation principle were given and verified experimentally. Experimental results show that the control method of this converter is feasible.